Heat exchanger

ABSTRACT

A protective cover 7 is disposed on an airflow upstream side of a tube 2. Even when relatively large flying materials such as gravel impinge against a radiator 1, the flying materials are prevented from directly striking the tubes 2. As the tube 2 can thus be protected from the relatively large flying materials such as gravel, the radiator 1 can continue operating, and the reliability of the radiator 1 can be improved.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a heat exchanger, and can beeffectively applied to a radiator of large construction machine such asbulldozer or a shovel loader and an agricultural machine such as atractor.

[0003] 2. Description of the Related Art

[0004] A large construction machine such as a bulldozer and a shovelloader and an agricultural machine such as a tractor are used inenvironments where relatively large flying materials such as gravelexist. Therefore, the possibility is extremely high that flyingmaterials such as gravel may impinge against a radiator of thesemachines.

[0005] Once the flying materials, such as gravel, damage tubes of theradiator, cooling water leaks out and the radiator is very likely tostop operating.

SUMMARY OF THE INVENTION

[0006] In view of the background described above, the invention isdirected to protect the tubes from relatively large flying materialssuch as gravel.

[0007] To accomplish the object, one aspect of the invention provides aheat exchanger comprising a plurality of tubes (2) arranged in parallelwith one another in an airflow direction, and allowing a fluid to flowtherethrough; header tanks (3) arranged at end portions of the tubes (2)in a longitudinal direction, and communicating with these tubes (2); andtube protective members (7) for protecting the tubes (2), disposed on anairflow upstream side of the tubes (2), and being separate members fromthe tubes (2).

[0008] This construction makes it possible to prevent relatively largeflying materials such as gravel from directly striking the tubes (2)even when the flying materials impinge against the heat exchanger, andthus to protect the tubes (2) from the relatively large flying materialssuch as gravel. Because the heat exchanger thus continues operating,reliability of the heat exchanger can be improved.

[0009] In another aspect of the invention, each of the tubes (2)described above is shaped into a compressed flat shape in such a fashionthat the airflow direction is coincident with a major diameterdirection; a fin (6) for increasing a heat transfer area with air isbonded to a compressed flat surface (2 a) of an outer surface of each ofthe tubes (2); and the fin (6) extends to a portion corresponding to thetube protective member (7) beyond an end portion of the tube (2) in themajor diameter direction.

[0010] According to this construction, the fin (6) and the tubeprotective member (7) encompass each tube (6). Therefore, the tube (2)can be reliably protected from the flying materials.

[0011] Incidentally, the tube protective member (7) may be a roundrod-like member.

[0012] Still another aspect of the invention provides a heat exchangercomprising a plurality of tubes (2) through which a fluid flows; andfins (6) each bonded to an outer surface of each of the tubes (2), forincreasing a heat transfer area with air; wherein the fin (6) extends toat least a front side of the tube (2) and encompasses the front side ofthe tube (2).

[0013] Still another aspect of the invention provides a heat exchangercomprising a plurality of tubes (2) through which a fluid flows; andfins (6) each bonded to an outer surface of each of the tubes (2), forincreasing a heat transfer area with air; wherein the tube (2) is shapedinto a compressed flat shape so that an airflow direction coincides witha major diameter direction, and the fin (6) is bonded to the compressedflat surface (2 a) in such a fashion as to substantially cover the wholearea of the compressed flat surface (2 a) of an outer surface of thetube (2).

[0014] Still another aspect of the invention provides a heat exchangercomprising a plurality of tubes (2) arranged in parallel with oneanother in an airflow direction, and allowing a fluid to flowtherethrough; header tanks (3) arranged at end portions of the tubes (2)in a longitudinal direction, and communicating with these tubes (2); andfins (6) each brazed to an outer surface of each of the tubes (2), forpromoting heat exchange between the fluid and air; wherein a tubeprotective portion (8) is formed by a filler metal on an airflowupstream side of the tube (2) when the filler metal is solidified in abrazing process of the tube (2) and the fin (6).

[0015] The present invention may be more fully understood from thedescription of preferred embodiments of the invention, as set forthbelow, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the drawings:

[0017]FIG. 1 is a perspective view of a radiator according to a firstembodiment of the invention;

[0018]FIG. 2 is a schematic view showing a mounting structure of aradiator according to the first embodiment of the invention;

[0019]FIG. 3 is a sectional view when the radiator according to thefirst embodiment of the invention is viewed from a longitudinaldirection of tubes;

[0020]FIG. 4 is an explanatory view useful for explaining operation andeffects of the radiator according to the first embodiment of theinvention;

[0021]FIGS. 5A and 5B are explanatory views each being useful forexplaining a radiator according to a second embodiment of the invention;

[0022]FIGS. 6A and 6B are explanatory views each being useful forexplaining a radiator according to a third embodiment of the invention;

[0023]FIG. 7A is an explanatory view being useful for explaining aradiator according to a fourth embodiment of the invention; and

[0024]FIG. 7B is an enlarged view of a portion A shown in FIG. 7A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

[0025] This embodiment represents the application of the invention to aradiator of a large construction machine such as a bulldozer or a shovelloader. FIG. 1 is a perspective view showing the appearance of theradiator 1 in this embodiment and FIG. 2 is a schematic view showing amounting state of the radiator 1.

[0026] The radiator 1 is mounted so that cooling air blown from a blower10 mounted on an upstream side of an air flow can blow onto the radiator1 as shown in FIG. 2. The blower 10 acquires power from an engine E/Gand is driven by this power.

[0027] As shown in FIG. 1, the radiator 1 includes a plurality of tubes2 made of aluminum, through which cooling water flows, and header tanks3 formed of aluminum, disposed at both ends of the tubes 2 in alongitudinal direction and communicating with the tubes 2. In thisembodiment, about 50 to about 100 tubes 2 and the header tanks 3communicating with these tubes 2 constitute one unit 4. When a pluralityof these units 4 is combined with one another, they constitute theradiator 1.

[0028] More concretely, second header tanks 5 communicating with theheader tanks 3 of each unit 1 connect the header tanks 3 to constituteone radiator 1. Incidentally, each unit 4 has a heat radiation capacityof from about 100 to about 200 W.

[0029] The tubes 2 of each unit 4 are flat tubes shaped into acompressed flat shape so that the flowing direction of air coincideswith a direction of a major diameter, and are arranged in parallel withone another relative to the air flowing direction. An aluminum fin 6 forincreasing a heat transfer area with air and for promoting heat exchangeis brazed to a compressed flat surface 2 a of the outer surface of eachtube 2 as shown in FIG. 3. These fins 6 are arranged in such a fashionas to describe a corrugated shape when viewed from the air flowingdirection (see FIG. 1).

[0030] The term “brazing” means a bonding technique that bonds anarticle by use of a brazing material or a solder without melting a basemetal. The technology using a filler metal having a melting point of450° C. or above is called “brazing” and the material used at this timeis called the “brazing material”. The technology using a filler metalhaving a melting point of 450° C. or below is called “soldering” and thefiller metal is called the “solder”.

[0031] A protective bar 7 as a round rod-like tube protective member isdisposed at an end portion of each tube 2 in its major diameterdirection and on the more upstream side of the air flowing directionthan the tube 2. The protective bar 7 is produced as a member separatefrom the tube 2 and at least both of its ends in the longitudinaldirection are brazed to the header tank 3. Each fin 6 extends to atleast a portion corresponding to this protective bar 7 beyond the endportion of the tube 2 in the major diameter direction.

[0032] Next, the operation and effects of this embodiment will bedescribed.

[0033] In this embodiment, the protective bar 7 is disposed on theairflow upstream side of the tube 2. Therefore, even when relativelylarge flying materials such as gravel impinge against the radiator 1,the flying materials are prevented from directly striking the tubes 2.In other words, as the tubes 2 can be protected from the relativelylarge flying materials such as gravel, the radiator 1 can be preventedfrom stopping its operation and reliability of the radiator 1 can beimproved.

[0034] As the fin 6 extends to the portion corresponding to theprotective bar 7 beyond the end portion of the tube 1 in its majordiameter direction, the fin 6 and the protective bar 7 encompass thetube 2, and the tube 2 can be reliably protected from the flyingmaterials.

[0035] Incidentally, the fin 6 extends to the portion corresponding tothe protective bar 7 beyond the end portion of the tube 2 in its majordiameter direction in this embodiment. However, the embodiment is notparticularly limited to this construction, and the fin 6 need not alwaysextend beyond the end portion of the tube 2 in its major diameterdirection.

[0036] The protective bar 7 is not limited to the round rod-like bar,either, but may be a round pipe, a rectangular rod or a rectangularpipe.

[0037] It may be possible to employ means for forming a protectivemember 7 a corresponding to the protective bar 7 integrally with thetube 2 as shown in FIG. 4. However, this means is not advantageousbecause the sectional shape of the tube 2 is distorted and the tube 2cannot be fitted and bonded easily to the header tank 3.

Second Embodiment

[0038] This embodiment does not use the protective bar 7 but extends thefin 6 to at least the front side of the tube 2 in such a fashion as tocover the front side of the tube 2 as shown in FIGS. 5A and 5B.Incidentally, the term “front side” of the tube 2 means the airflowupstream side of the tube 2.

[0039]FIG. 5A is a sectional view when the tube 2 and the fin 6 areviewed from the longitudinal direction of the tube 2, and FIG. 5B is afront view when the tube 2 and the fin 6 are viewed from the airflowupstream side.

[0040] As the fin 6 covers the tube 2 in this way, the flying materialsare prevented from directly impinging against the tube 2. Therefore,because the tube 2 can be protected from the relatively large flyingmaterials such as the gravel, the radiator 1 can continue operating, andthe reliability of the radiator 1 can be improved.

Third Embodiment

[0041] In the foregoing embodiments, the fin 6 is shaped into arectangular wave shape or a sine wave shape. In this embodiment,however, the fins 6 shaped into the rectangular wave shape are crushedin the traveling direction of the wave in such a fashion as to describea truss structure as shown in FIGS. 6A and 6B. In consequence, the fins6 are brazed to the compressed flat surfaces 2 a of the tubes 2 so as tocover substantially the full areas of the compressed flat surfaces 2.

[0042]FIG. 6A is a perspective view of the tubes 2 and the fins 6, andFIG. 6B is a front view of the tubes 2 and the fins 6 when they areviewed from the airflow upstream side.

[0043] According to this construction, the fins 6 cover substantiallythe whole area of the compressed flat surfaces 2 a, and the flyingmaterials are prevented from directly striking the compressed flatsurfaces 2 a of the tubes 2. Consequently, as the tube 2 can beprotected from the relatively large flying materials such as the gravel,the radiator 1 can continue operating, and the reliability of theradiator 1 can be improved.

[0044] In this embodiment, the flying materials may directly impingeagainst the end portion of the tubes 2 in the longitudinal direction.However, the fin 6 extends to the airflow upstream side beyond the endportion of the tube 2 in the major diameter direction as shown in FIG.6A. In practice, the possibility that the flying materials directlyimpinge against the end portion of the tube 2 in the major diameterdirection is low, but when the protective bar 1 is provided in the sameway as in the first embodiment, the tube 2 can be protected morereliably from the flying materials.

[0045] By the way, the fin 6 extends to the upstream side beyond the endportion of the tube 2 in the major diameter direction in thisembodiment. However, the embodiment is not particularly limited to thisconstruction, and the fin 6 need not always extend the end portion ofthe tube 2 in the major diameter direction.

Fourth Embodiment

[0046] In this embodiment, the width of each fin 6 is increased so thatthe fin 6 reaches the airflow upstream side beyond the end portion ofthe tube 2 in the major diameter direction, as shown in FIGS. 7A and 7B.In this instance, a greater amount of the filler metal is applied to theouter surface of the tube 2 than in the foregoing embodiment so thatwhen solidified, the filler metal connects the fin 6 to another fin 6 onthe airflow upstream side of the tube 2 during brazing, and the fillermetal forms the tube protective portion 8 as shown in FIG. 7B.

[0047] In this way, the flying materials are prevented from directlyimpinging against the tube 2 and the tube 2 can be protected from therelatively large flying materials such as the gravel. Therefore, theradiator 1 can continue operating and the reliability of the heatexchanger can be improved.

[0048] In this embodiment, the filler metal forms the tube protectiveportion 8. Therefore, it is necessary to conduct brazing while the units4 are arranged inside a furnace in such a fashion as to be positionedeither on the airflow upstream side or downstream side of the units 4.

[0049] In this embodiment, for example, in case of a radiator made ofaluminum or aluminum alloys, the tube 2 is formed of a material selectedfrom the JIS (Japanese Industry Standard), A6000 group, the fin 6 isformed of a material selected from the JIS, A7000 group, and the fillermetal is a material selected from the JIS, A4000 group.

[0050] Though the filler metal is coated in this embodiment, theembodiment is not limited thereto. For example, spray coating may beemployed, too. In the heat exchanger of the present invention, besidesthe aluminum or aluminum alloys as the material of the heat exchanger,copper or copper alloys can be used.

[0051] The foregoing embodiments represent the modular type radiatorcomprising the combination of a plurality of units 4, but the inventionis not particularly limited thereto.

[0052] The invention is not particularly limited to the specificapplication such as construction equipment but can also be applied to aradiator of a passenger car, for example.

[0053] While the invention has been described with reference to specificembodiments chosen for purpose of illustration, it should be apparentthat numerous modifications could be made thereto by those skilled inthe art without departing from the basic concept and scope of theinvention.

1. A heat exchanger comprising: a plurality of tubes arranged inparallel with one another, and allowing a fluid to flow therethrough;header tanks arranged at end portions of said tubes in a longitudinaldirection, and communicating with said plurality of tubes; and tubeprotective members for protecting said tubes, disposed on an airflowupstream side of said tubes, and being separate members from said tubes.2. A heat exchanger according to claim 1, wherein each of said tubes isshaped into a compressed flat shape in such a fashion that the airflowdirection is coincident with a major diameter direction; a fin forincreasing a heat transfer area with air is bonded to a compressed flatsurface of an outer surface of each of said tubes; and said fin extendsto a portion corresponding to said tube protective member beyond an endportion of said tube in the major diameter direction.
 3. A heatexchanger according to claim 1, wherein said tube protective member isaround rod-like member.
 4. A heat exchanger comprising: a plurality oftubes through which a fluid flows; and fins each bonded to an outersurface of each of said tubes, for increasing a heat transfer area withair; wherein said fin extends to at least a front side of said tube andencompasses the front side of said tube.
 5. A heat exchanger comprising:a plurality of tubes through which a fluid flows; and fins each bondedto an outer surface of each of said tubes, for increasing a heattransfer area with air; wherein said tube is shaped into a compressedflat shape so that an airflow direction coincides with a major diameterdirection, and said fin is bonded to said compressed flat surface insuch a fashion as to cover substantially the whole area of saidcompressed flat surface of an outer surface of said tube.
 6. A heatexchanger comprising: a plurality of tubes arranged in parallel with oneanother, and allowing a fluid to flow therethrough; header tanksarranged at end portions of said tubes in a longitudinal direction, andcommunicating with said plurality of tubes; and fins each brazed to anouter surface of each of said tubes, for promoting heat exchange betweensaid fluid and air; wherein a tube protective portion is formed by afiller metal on an airflow upstream side of said tube when said fillermetal is solidified in a brazing process of said tube and said fin.